Y’know, when I’m really old and past my prime, I expect to watch a lot of TV and take naps.

But when NASA’s missions are old and having trouble, they produce images like this:

Whoa. Click to embiggenate.

Spitzer Space Telescope is an infrared observatory that launched in 2003. Infrared light is emitted by warm objects: dust, stars, gas, planets, and so on. That includes the telescope itself: unless cooled, the mirror and the rest of the telescope will glow brightly in the infrared, making it impossible to do any science. It would be like shining a flashlight down the ‘scope! So Spitzer uses liquid helium to cool some of its instruments down almost to absolute zero.

Or, I should say it "used" liquid helium: over time, the helium warms up, and in May 2009 the last of the liquid helium boiled away. What this means is that some of the detectors on board Spitzer are no longer usable.

However, Spitzer has a sun shade that keeps it passively cooled to about 30K (-400 F) , so two of the detectors are still running just fine, as evidenced by the image above! Taken with those remaining "channels" — which see 3.6 and 4.5 micron light, roughly 4 and 6 times the wavelengths our eyes can see –it shows the star forming region DR22, a giant cloud of gas and dust with a young cluster of stars in its heart. Those stars are less than a million years old, so they’re infants on a galactic scale. Winds and UV light from those stars are carving up the surrounding nebulosity, sculpting it into sheets and blowing out a cavity in the middle.

I’m curious about the short diagonal streak in the upper left of the image; it doesn’t look like a galaxy or a filament. I’ve sent a letter to the folks at Spitzer to get more info. [Update: Word back from Spitzer is that it is a galaxy. Weird!]

Along with DR22, a pretty image of the planetary nebula NGC 4361 was released. This is a star at the end of its normal life; it is ejecting a wind of particles like the solar wind but far, far denser. Images like this from Spitzer can tell us how much warm dust is generated in the star, and give diagnostics needed to understand how stars like the Sun eventually die.

You can see the star itself smack dab in the center of the nebulosity. Take a good look: that’s us in about 7 billion years time. It’s not entirely certain if the Sun will be hot enough to create such a beautiful nebula as seen here — it takes a star somewhat more massive than the Sun to leave behind a hot enough corpse to get the gas to glow — but what happens to us is not all that different than what happened to the central star of NGC 4361.

Spitzer will be used by astronomers for years to come, even though in many ways it’s not up to 100% power. But these images go to show you the advantages and abilities of space-borne telescopes; even when they’re down, they’re definitely not out.

Okay, this is probably a dumb question, but since you’re talking about young stars…. Is there a moment when the new star “ignites”? When the collapsing cloud of gas and dust “turns on”? Or is it more of a gradual process and there’s no line of demarcation when you can say that it’s changed from the cloud of gas and dust to the star? Thanks.

If the cloud is massive enough, it’ll collapse until the weight of the outer layers compacts the core tightly enough for nuclear fusion. Once the fusion commences, it’s a star. (Because of random walk dynamics, it then takes quite some time for the light radiation to percolate all the way up to where the density drops to the point of transparency, at which it becomes visibly starlike from the outside. Calculations show that this can take millennia.)

@Bunny: Shh … it takes a looong time to get through the entire checklist then calibration and tests before getting the science data in. Then someone’s got to process it and they might want to get something together for publication before they dare put pretty pictures out there. Personally I don’t see why people don’t just put the pictures out; without the raw data you really can’t do much except stare at the picture. Exceptions of course are if you happen to be looking at something that makes other people go “aha!” and pull out old observations and beat you to publishing something.

Now does this telescope have a secondary suspended by 3 or 6 vanes? The 6-pointed diffraction pattern on the brighter stars is annoying.

@Bunny: The Herschel science demonstration phase (SDP) is currently scheduled for late october, early november, following the end of the checkout phase. This is when the science teams get their first shot at something ‘real’. The SDP phase is short, so the teams tend to shoot for something they think will be spectacular, bright, easy(!) and hopefully worthy of a press release. I’m guessing results will be coming out around New Year – early spring 2010. The good news is that everything seems to be performing really well, perhaps even better than expected!

Can the Spitzer theoretically be “serviced”? I mean I doubt it’s in the works or anything, with the impending shuttle retirement. But was it designed to allow someone to go up there and “recharge” its liquid helium tanks? It hasn’t been up there that long. I would be surprised if they didn’t plan for this.

That’s about 1.5M Km from the earth so it will take time to get there, then a stable orbit needs to be established, then final system checks can be performed. So with any luck we’ll see some pretty pictures before Christmas. Personally I can’t wait to see the infrared images; I hope they have no problems deploying the telescope.

Spitzer cannot be serviced, because it is not in orbit around the Earth like Hubble. Spitzer was basically “shot out” into space and has been following an Earth trailing orbit around the Sun for 6 years now, receding from Earth at roughly 10 million km per year. It is way (waayyyyyy) beyond the point where we have any space vehicle that can take us to it.

However, this actually was part of the design. Spitzer’s minimum lifetime was 2.5 years, and its “goal” lifetime was 5 years. It ended up lasting over 5.5 years! And it will continue to last several more years in what we call the “warm phase,” which only involves the two short-wavelength cameras that you see in the picture above.

Hubble was truly a unique telescope in that it was able to be serviced while in use, to my knowledge no other space telescope has that capability, nor are future missions being planned with the idea that they can be serviced if something goes wrong.

I’d be very surprised if the satellite is servicable, and if servicing was ever seriously considered. I don’t think that on-orbit transferring of cryogens is something anyone is yet equipped to do. The Alpha Magnetic Spectrometer, once it’s carried up, will have a three year supply of liquid helium; but it isn’t servicable in that respect, and it’ll be attached to the space station with people and docking ports right there.

Hubble really is the only orbiting telescope made to be serviced. Several other space telescopes have done their time and been retired, and they didn’t even have cryogenics aboard.

Do they use helium as the working fluid for a compressor cooling system? Is the helium loss due to migration of the helium thru seals? Clue me in here. I have no idea how that coolant system works. Even Wiki makes no mention of the He coolant system,,,

,,,and it just occurs to me, we could boost such a scope to the orbit of the the mini-planet Arf,,,er,I mean, Pluto. then it wouldn’t much matter if it ran out of coolant,,,

Ok, I got around to checking Plutos surface temp. 33kelvins,,,SO, never mind,,,

The liquid helium is used because it’s just plain cold (no compressor needed), just a few Kelvins. It runs out because, to keep it cold, it has to be allowed to slowly boil off into space. The escaping vapor carries away the acquired heat which otherwise would drive up the temperature of the whole supply of helium. The controlled loss allows what’s left to stay at equilibrium.

@ 22 Spitzer : Spitzer was basically “shot out” into space and has been following an Earth trailing orbit around the Sun for 6 years now, receding from Earth at roughly 10 million km per year.

Where will ultimately end up if it keeps drifting? Will it drift out into an independent solar orbit or end up eventually (after 100’s of years?) returning to the vicinity of Earth
again?

It is way (waayyyyyy) beyond the point where we have any space vehicle that can take us to it.

Yet.

Seriously, lets be a bit optimistic about our future potential shall we? Who knows in a hundred years time maybe we’ll pick it up for pride of place in a museum – or better yet refill its liquid helium coolant & get it going again! Y’know as a historic restoration project idea or suchlike?

Thanks for that. I was wondering how they could run out. Now, since my refrigerator will run for 20-30 years and never need a coolant refill because the compressor/coolant system is sealed, I really have to wonder why that was not the preferred system on Spitzer. I’m sure there were quite practical reasons(mass of the compressor vs mass of Helium, reliability of mechanical components,etc) but I’ve never seen the rationale explained. As far as mechanical compressors are concerned, I recall reading an article about an electrophoretic pump, that could generate 5000 psi, which might be enough to compress He w/o moving parts,,,

In a hundred years you don’t want to refill Spitzer and keep it going again. Those who are in charge then will probably think, “look at this little ‘scope; almost from the stone-age”. So, probably it could find its way into a museum, but I guess it is more likely that it will drift through space forever alone……..

@ Gary Ansorge

You should not compare your refrigerator to a system cooling with liquid Helium . Even that you have moving parts and the pump in your system will generate a lot of heat due to friction (laws of thermodynamics). And Helium is only liquid below a few Kelvin. So even a little heat of friction will actually lead to boiling of the Helium and to high pressures in the system that could lead to explosions and the destruction of the whole ‘scope (remember the LHC and why it was shut down again last autumn – just due to liquid Helium turning gaseous again and thus creating a tremendous amount of pressure).

@Gary: cooling in space is a whole different ballgame and many techniques are employed including simply allowing an object to radiate into space. When the necessary operating temperatures are too low to be achieved via passive radiation to space, cryogens are used. Mechanical compressors are generally frowned upon (high power consumption, large space, large weight, difficult to dissipate heat, bad vibrations) although if I’m not too senile a few earth observing instruments did fly with a Stirling cooler. In some instances an exotic device like a “pulse tube cooler” can be used. When operating temperatures of a few K are essential, liquid helium is the best option so far even though it will ultimately all be vaporized and slowly bleed into space as designed.

If you look close in the lower left quadrant you can see Jesus with angels wings and a shepherds crook, or a pirate sword (whatever!) In the lower right is one of the 3 musketeers , and in the upper left its mickey mouse in a foot ball helmet. Take your pick.